flutter单边阴影

  decoration: BoxDecoration(color: Colors.white, boxShadow: [
          BoxShadow(
              color: Color(0x2B000000),
              offset: Offset(0.0, 5.0), //阴影xy轴偏移量
              blurRadius: 15.0, //阴影模糊程度
              spreadRadius: -11 //阴影扩散程度
              )
        ]),